☣️ UN 2501 • CLASS 6
Tris-(1-aziridinyl)phosphine oxide, solution
Placard: Toxic. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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Quick details
UN 2501
Class: 6
Placard type: Toxic
ERG: Guide 152 (check current ERG)
Isolation: ERG 152: isolate spill 25m all directions; if tank/rail car involved in fire, isolate 800m all directions and consider evacuation
Chemical & Response Details
| Also known as | TEPATris(1-aziridinyl)phosphine oxideTriethylenephosphoramideAPOTris(ethylenimino)phosphine oxide |
| CAS Number | 545-55-1 |
| Appearance | Colorless to pale yellow liquid solution. Odorless or slight amine-like odor. Highly toxic organic compound used historically as a chemotherapy agent and insect chemosterilant. |
| Flash Point | Not available for solution; base compound is combustible |
| Boiling Point | Decomposes before boiling at approximately 80-100°C (176-212°F) |
| Vapor Density | Heavier than air (MW ~173) |
| Water Reactivity | Soluble in water; no violent reaction but releases toxic vapors |
| Extinguishing | Alcohol-resistant foam, CO2, dry chemical; water spray for cooling only |
| PPE | ⚠️ Level A required; full encapsulation, SCBA, chemical-resistant suit; avoid all skin contact - causes severe burns and systemic toxicity |
| Isolation | ERG 152: isolate spill 25m all directions; if tank/rail car involved in fire, isolate 800m all directions and consider evacuation |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- Highly toxic, may be fatal if inhaled, ingested or absorbed through skin.
- Contact with molten substance may cause severe burns to skin and eyes.
- Avoid any skin contact.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental
- Combustible material: may burn but does not ignite readily.
- Containers may explode when heated.
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
First actions (field-minded)
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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UN 2501 — Tris-(1-aziridinyl)phosphine oxide, solu HAZMAT RADIO NOTE — UN 2501
Product: Tris-(1-aziridinyl)phosphine oxide, solution
Class 6 / Toxic / ERG 152
PPE: Level A required; full encapsulation, SCBA, chemical-resistant suit; avoid all skin contact - causes severe burns and systemic toxicity
ISOLATION: ERG 152: isolate spill 25m all directions; if tank/rail car involved in fire, isolate 800m all directions and consider evacuation
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 2501 — Tris-(1-aziridinyl)phosphine oxide, solution
Class: 6 | Placard: Toxic | ERG Guide: 152
Appearance: Colorless to pale yellow liquid solution. Odorless or slight amine-like odor. Highly toxic organic compound used historically as a chemotherapy agent and insect chemosterilant.
Water Reactivity: Soluble in water; no violent reaction but releases toxic vapors
Extinguishing: Alcohol-resistant foam, CO2, dry chemical; water spray for cooling only
PPE: Level A required; full encapsulation, SCBA, chemical-resistant suit; avoid all skin contact - causes severe burns and systemic toxicity
Isolation: ERG 152: isolate spill 25m all directions; if tank/rail car involved in fire, isolate 800m all directions and consider evacuation
— Key Hazards —
• Highly toxic, may be fatal if inhaled, ingested or absorbed through skin.
• Contact with molten substance may cause severe burns to skin and eyes.
• Avoid any skin contact.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
SOURCE: allfirefighter.com/hazmat/un/2501 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2501 Tris-(1-aziridinyl)phosphine oxide, solution Cls6 ERG152 | allfirefighter.com/hazmat/un/2501SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions. Page: https://allfirefighter.com/hazmat/un/2501
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FAQ
Highly toxic, may be fatal if inhaled, ingested or absorbed through skin. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental Combustible material: may burn but does not ignite readily. Containers may explode when heated. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level A required; full encapsulation, SCBA, chemical-resistant suit; avoid all skin contact - causes severe burns and systemic toxicity
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 152 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles. This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.